Rare earth ion doped GOS (Gd2O2S) ceramic scintillators, compared with traditional scintillation single crystals comprising CsI, CdWO4, have advantages such as density and light-production are high, chemical properties are stable, the preparation process is relatively simple, process may be performed without cleavage, so they have become the ideal and best scintillator materials having the most comprehensive performance for various radiation inspection detectors, such as X-ray CTs, high-speed X-ray scanner Detectors. Pr, Ce ion doped GOS ceramic scintillators have a very low afterglow, so they are ideal scintillators for CT radiation detector.
Currently, GOS ceramic scintillators are generally manufactured by uniaxial-compression-sintering. Usually, a prepared GOS powder is placed into a straight-tube-shaped mold having upper and lower pressing heads to perform hot-pressing-sintering. In U.S. Pat. Nos. 5,296,163, 8,025,817, and CN 105439561 A, methods of preparing GOS ceramic scintillators by uniaxial hot-pressing were discussed, and in CN 105330289A, a method of preparing GOS ceramic scintillators by uniaxial discharge plasma was discussed. A structure of a common uniaxial pressure sintering mold for manufacturing GOS ceramic scintillators is shown in FIG. 1. The mold consists of a female outer sleeve 101 and a male pressing head 102. The female outer sleeve 101 has a cylindrical shape with a center through hole. The male pressing head 102 comprises an upper pressing head and a lower pressing head both fit with the center through hole of the female outer sleeve 101, such that a GOS ceramic powder is pressed by a hot-pressing driving in an axial relative movement to form scintillators.
Because a high axial pressure and a high temperature are necessary, such uniaxial pressure sintering mold has very high requirement for mold materials. Therefore, generally, the mold has a round cavity such that the pressing force may be uniformly distributed to the mold when the hot-pressing-sintering to the powder is performed, to avoid damage to the mold due to stress concentration, thus realizing reusing of the mold. However, because the powder would be in a semi-flow state in conditions of high temperature and high pressure, the sintered ceramic blocks are tightly pressed onto the inner wall of the female outer sleeve 101, and the GOS ceramic has a relatively higher strength, and a damage will occur in the inner wall of the female outer sleeve 101 in stripping. Accordingly, after several times of re-using, the inner diameter of the female outer sleeve 101 will gradually become larger, and the fit clearance between the female outer sleeve 101 and the male pressing head 102 will be larger and larger, resulting failure of the mold.
In addition, since the GOS ceramic scintillators are generally required to be cut into rectangular strip structures in use, for facilitating cutting, as shown as in FIG. 2, generally a round GOS piece 200 has to be cut into a practically useful square part 201, leaving the surrounding arcuate parts 202 not available for scintillator process, to cause waste of material.